Polyvinyl acetal resin sheets containing triamyl phosphate



I Patented Dec. 26, 1939 UNITED STATES PATENT OFFICE POLYVINYL ACETAL RESIN SHEETS CON- TAINING TRIAMYL PHOSPHATE Henry B. Smith, Rochester, N. Y., assignor to Eastman Kodak Company, Rochester, N. Y., a

No Drawing.

corporation of New Jersey pplication December 22, 1937, Serial No. 181,223

5 4 Claims. (01. 260- -36) 5 One object of this invention is to produce compositions of matter which may be made into permanently transparent, strong and flexible sheets or films of desired thinness which are substantially waterproof, are unaffected by ordinary 10 photographic fluids and. possess the desired properties of a support for sensitive photographic,

coatings. Another object of my invention is to produce compositions of matter which can be made into sheets suitable for use in laminated, l5 shatter-proof glass. Still-another object is to produce compositions which can be rolled, extruded, molded or otherwise worked into relatively thick sheets and massive plastics. A further object is to produce. compositions suitable 20 for use in lacquers, artificial silk filaments, wrapping tissues and the like. Other objects will hereinafter appear.

I have discovered that triamyl phosphate is a very useful conditioning agent for polyvinyl g acetal resins. Not only does it serve as a plasticizer in the accepted sense of the term, increasing the flexibility and toughness of polyvinyl acetal resin films, sheets, or other objects or masses containing it, but-when used in amounts about 40 or more parts per 100 parts. of certain of the polyvinyl acetal resins, namely the polyvinyl acetal resins in which a predominating proportion of the acetal groups are acetaldehyde acetal groups or butyraldehyde acetal groups, it 5 has an unusual and remarkable eife'ct'which I may call elastlcizing. 'That is to say, a sheet of polyvinyl acetaldehyde or butyraldehyde acetal ,resin containing about 40 or more parts of tris amyl phosphate per 100 parts of resin possesses 40 the property which, in the rubber industry, is known as nervej: namely, the property of stretching to a considerable extent when tension is exerted upon it, and returning to its original dimensions when the tension is released. This 45 property renders .such sheets, which I shall call rubbery sheets, particularly useful in the manufacture of shatter-proof glass. Tri'amyl phosphate alsodecreases the flammability of poly-' vinyl acetal resin compositions'or objects con- 50 taining it.

For the manufacture of cast films or sheets,

the polyvinyl acetal resin and triamyl phosphate may be dissolved in,'.a suitable solvent or solvent mixture, such, for instance, as acetone, methanol, acetone methanol mixtures, ethylene 'chloride-methanol mixtures,-etc., about 300 to 500 or more parts of the solvent or solvent mixture being'used per 100 parts of the resin. From about 2 to 100 parts or more of triamyl phosphate per 100 parts of resin may be employed, 5

depending upon the nature of the resin and the purpose for which the sheets are to be "used. Suitable proportions of triamyl phosphate for any resin and any purpose may be readily determined by experiment. For the manufacture of sheets suitable for photographic film base, from 2 to 25 parts of triamyl phosphate per 100 parts of resin are suitable. The resin solution is cast as a sheet, the solvent evaporated, and the sheet stripped from the casting surface. Sheets for use in laminated glass may be formed by casting, or may be made without the use of volatile solvent by extrusion, for example in the manner set forth in application Serial .No. 147,934 of John S. Kimble and Ernest C. Blackard, filed June 12, 1937. For instance, 40 or more parts of triamyl phosphate and 100 parts of a polyvinyl acetaldehyde or butyraldehyde acetal resin may be mixed in a suitable, jacketed mixerat a low temperature, for example 10 C., and the mixture may then be worked on hot rolls, in the manner described in U. S. Patent 2,048,686 of F. R. Conklin, until complete homogenization has taken place. The mass thus produced may then be extruded through an annular die, and the tube so formed slit to form a sheet. The polyvinyl acetal resins can be prepared .by reacting polyvinyl alcohol with an aldehyde in the presence of an acetal condensation catalyst, e. g. a mineral acid. These resins can also be prepared by simultaneously de-estei'ifying a poly vinyl aliphatic ester and reacting the de-esterification product with an aldehyde in the presence of. a de-esterifying catalyst and acetal condensation catalyst. Mineral acids are catalysts for 40 both de-esterification and acetal formation. Among the polyvinyl acetal resins with which triamyl phosphate is useful may be mentioned, as illustrative examples, the polyvinyl formaldehyde acetal resins, the polyvinyl acetaldehyde acetal resins, the polyvinyl formaldehyde acetaldehyde mixed acetal resins, the polyvinyl butyraldehyde acetal resins, and the polyvinyl butyraldehyde acetaldehyde mixed acetal resins.

Examples of the preparation of polyvinyl formaldehyde acetal resins may be found in US. Patent 1,955,068,=Examples l, 4 and 5; in U. S..Patent 2,036,092,-Examples 1, 2, 3, '7 and 8; in British Patent 454,691, Examples 1, 2, 3, 4, 5, 6 and 7; in British Patent 404,279, Example 3; and in British for stabilizing the resin, 5.25 lbs. of trioxymethylene, and 6.25 lbs. of I101. The reaction mixture was allowed to stand for 5 days at 0., after which it was diluted with acetic acid. The resin was precipitated by pouring into cold water, washed and dried. Analysis showed the resin to have an acetate group content equivalent to 10.6% by weight of polyvinyl acetate and a hydroxyl' group content equivalent to 7.1% by weight of polyvinyl alcohol. The stabilization of polyvinyl acetal resins by hydroxylamine is claimed in the application of Joseph B. Hale, Serial No. 149,916, filed June 23, 1937, Patent No. 2.146.735.

Examples of the preparation of polyvinyl acetaldehyde acetal resins may be found in U. S. Patent 2,044,730, Example 1; U. S. Patent 1,955,068, Example 2; U. S. Patent 2,036,092, Examples 4, 5 and 6; British Patent 466,598, Examples 1, 2, 3, 4 and 7; British Patent 404,279, Examples 1, 2, 4, 5, 6, 7 and 8; U. S. Patent 1,990,399; and French Patent 808,578, Examples 1, 2 and 3.

Additional examples of the preparation of polyvinyl acetaldehyde acetal resins are as follows:

100 lbs. of polyvinyl acetate, the viscosity of whose molar solution in benzene was 45 centipoises, was dissolved in 300 lbs. of ethyl alcohol. To this solution were added 30 lbs. of paraldehyde and 25 lbs. of 35% HCl. The reaction mixture was allowed to stand for 4 days at 40 C., after which it was diluted with ethyl alcohol, and the resin precipitated by pouring into cold water, washed and dried. Analysis showed the resin to have an acetate group content equivalent to 2.1% by weight of polyvinyl acetate and a hydroxyl group content equivalent to 12.9% by Weight of polyvinyl alcohol.

25 lbs. of polyvinyl acetate, the viscosity of whose molar solution in benzene was 45 centipoises, was dissolved in 75 lbs. of 95% ethyl al.- cohol. To this solution was added 8 lbs. of paraldehyde and a solution of 3 lbs. 12 ozs. of sulfuric acid in 3 lbs. 12 ozs. of 95% ethyl alcohol.

The reaction mixture was allowed to stand for 7 days at 40 C., after which it was diluted with ethyl alcohol, and the resin precipitated by pouring into cold water, washed, and dried. Analysis showed the resin to have an acetate group content equivalent to 1.7% by. weight ofpolyvinyl acetate and a hydroxyl group content equivalent to 13.8% by weight of polyvinyl alcohol.

Examples of the preparation of polyvinyl formaldehyde acetaldehyde mixed acetal resins may be found in British Patent 430,136, Examples 1, 2, 3, 4, 5 and 6; British Patent 445,565,; Example 2; British Patent 465,873, Examples 1, 2, 3, 4, 5 and 6; French Patent 808,586, Examples 1, 2, 3, 4, 5, 6, 12, 13, 14, 15, 16, 17, 18 and 19.

Additional examples of the preparation of polyvinyl formaldehyde acetaldehyde mixed acetal resins are given in the application of- Ralph H. Talbot, Serial No. 85,960, filed June 18, 1936, as follows:

Example 1 parts (1.16 mol. calculated as monomeric vinyl acetate) of a polyvinyl acetate (45 centipoises), 100 parts of ethyl alcohol, parts of ethyl acetate, 34 parts (.77 mol. as monomeric acetaldehyde) of paracetaldehyde and 5.8 parts (.196 mol. as monomeric formaldehyde) of paraformaldehyde were placed in an enamelled vessel and brought into solution by stirring. When solution was complete, 10 parts of sulfuric acid (sp. g. 1.84) in 10 parts of water were added, and the mixture stirred. The mixture was maintained at a temperature of 40 C. for 144 hours. The contents of the vessel were then diluted with about two and a half volumes of acetone, and the mixture precipitated into water. The precipitated resin was washed free from impurities by repeated changes of cold water, and dried. The resin, when analyzed, gave a hydroxyl group content equivalent to about 6.4 per cent by weight of polyvinyl alcohol, an acetate group content equivalent to about 4.0 per cent by weight of polyvinyl acetate, a formaldehyde acetal group content equivalent to about 15.9 per cent by weight of polyvinyl formaldehyde acetal and an acetaldehyde acetal group content equivalent to about 73.9 per cent by weight of polyvinyl acetaldehyde acetal. The polyvinyl acetal portion of the resin was therefore made up of about 19.7

'per cent by moles of polyvinyl formaldehyde "Example 2 50 parts (.58 mol. as monomer) of polyvinyl acetate (45 centipoises), 50 parts of ethyl alcohol, 90 parts of ethyl acetate, 17 parts (.385 mol. as monomer) of paracetaldehyde, 2.9 parts (.098 mol. as monomer) of paraformaldehyde, 5 parts of sulfuric acid and 5 parts of water were treated as in Example 1 for 161 hours. The well washed and dried resin gave upon analysis a hydroxyl group content equivalent to about 9.6% by weight of polyvinyl alcohol, an acetate group content equivalent to about 4.1% by weight of polyvinyl acetate, a formaldehyde acetal group content equivalent to about 13.9 per cent by weight of polyvinyl formaldehyde acetal, and an acetaldehyde acetal group content equivalent to about 69.9 per cent of polyvinyl acetaldehyde acetal. The polyvinyl acetal portion of the resin was therefore made up of about 18.5 percent by moles of polyvinyl formaldehyde acetal and 81.5 per cent by moles of polyvinyl acetaldehyde acetal. The resin was soluble in acetone to an extent which permitted coating a film or sheet from the resin.

Example 3 1300 parts (15.1 mol. as monomer) of a polyvinyl acetate (45 centipoises), 1700 parts of ethyl acetate, 2250 parts of ethyl alcohol (95%) and 48 parts (1.57 mol. as monomer) of paraformaldehyde (trioxymethylene) were placed in a vessel equipped with a reflux condenser and a means of agitation, and the contents brought to a temperature of about 70 C. by means of steam heating. 182.25 parts of sulfuric acid (sp. g. 1.84) dissolved in 51.5 parts of water were added, and the whole was heated at about 70 C. for about five hours, agitating throughout. At this point, 266.4 parts (6.05 mol. as monomer) of paracetaldehyde were added and heating at about 70 C. with agitation was continued for a further period of twenty hours. The contents of the reaction vessel were neutralized with ammonium hydroxide and diluted with water precipitating the resin as a cake. The cake was cut into small pieces and repeatedly washed with hot water until the resin was free from solvents, salts and other impurities. The resin, upon analysis, showed a hydroxyl group content equivalent to about 10.1 per cent by weight of polyvinyl alcohol, an acetate group content equivalent to about 3.2 per cent by weight of polyvinyl acetate, the remainder of the weight of the resin being polyvinyLacetal. The polyvinyl acetal portion of the resin was made up of about per cent by moles of polyvinyl acetaldehyde acetal and about 20 per cent by moles of polyvinyl formaldehydeacetal. The resin was not quite soluble in acetone, but could be made to dissolve by admixing small amounts of other solvents, such as alcohols, with the acetone.

Examples of the preparation of polyvinyl butyraldehyde acetal resins may be found in U. S.

Patent 2,044,730, Examples 2, 5 and 6; British Patent 466,598, Example 5; French Patent 813,- 303, Example 1; French Patent 813,514, Examples 1, 2, 3 and 4; and British Patent 459,878, Examples 1, 2, 5, 6, '7, 8, 9 and 10. b

An additional example of the preparation of a polyvinyl butyraldehyde acetal resin is as follows:

23.6 lbs. of polyvinyl acetate, the viscosity of whose molar solution in benzene was 45 centipoises, was dissolved in 56.5 lbs. of ethyl alcohol. butyraldehyde and 5.9 lbs. of 35% HCl. The reaction mixture was allowed to stand for 4 days at 40 C., after which it was diluted with ethyl alcohol and acetic acid, and the resin precipitated by pouring into cold water, washed, and dried.

To this solutions was added 7.9 lbs. of"

Analysis showed the resin to have an acetate group content equivalent to 3.1% by weight of polyvinyl acetate and a hydroxyl group content equivalent .to 16.3% by weight of polyvinyl alcohol.

An example of the prepation of a polyvinyl butyraldehyde acetaldehyde mixed acetal resin is given in French Patent 813,303, Example 2.

What I claim as my invention and desire to be secured by Letters Patent of the United States is:

.1. A transparent, rubbery sheet comprising parts of a polyvinyl acetal resin in which a predominating pro-portion of the acetal groups are selected from the group consisting of acetaldehyde acetal groups andbutyraldehyde acetal groups, and at least 40 parts, approximately, of

"triamyl phosphate as an elasticizer therefor.

2. A transparent, rubbery sheet comprising 100' partsof a polyvinyl acetaldehyde acetal resin and at least 40 parts, approximately, of triamyl to the sheet a rubbery character without substantially impairing its transparency.

HENRY B. SMITH. 

